Suspended roof structure for furnace heating chambers



J. RAWLINGS Jan. 5, 1954 SUSPENDED ROOF STRUCTURE FOR FURNACE HEATING CHAMBERS Filed Dec. 31, 1948 mmvroze JOHN RAWLINGS Patented Jan. 5, 1954 SUSPENDED ROOF STRUCTURE FOR FUR- NACE HEATING CHAMBERS John Rawlings, Swissvale, Pa., assignor of onehalf to Ralph T. Hadley, Sharon, Pa.

Application December 31, 1948, Serial No. 68,512

8 Claims.

This invention relates to heating chamber structure, particularly in a removable cover of suspended arch construction for an ingot heating furnace, otherwise known as a soaking pit.

Conventional suspended arch construction for a soaking pit cover comprises a series of parallel flanged metal stringers and rows of refractory blocks suspended beneath the stringers by means of integral hanger portions projecting above the suspended blocks and overlapping the flanges of the stringers. The rows of suspended blocks in some constructions are spaced apart and intermediate rows of blocks are keyed between and are supported by the suspended blocks. All of the blocks are arranged in a single layer with their lower surfaces in a common horizontal plane and their weight is supported by the overhead stringers. The suspended blocks must be strong to be self-supporting and are made of the highest quality of fire-clay. Such high quality blocks have relatively high strength but are expensive and also are brittle and easily cracked, especially when ingots suspended by a crane are brushed against the cover or when the cover is being moved about by a crane. The integral hanger of each suspended block has a relatively small neck and relatively small projections engaging the supporting stringers and the said neck and projections are particularly likely to crack and thereby destroy the supporting connection between the body of the suspended block and the stringers overhead. The blocks in the cover are also subject to injury through spalling of their lower This is caused by rough handling and by uneven expansion or contraction of the blocks when a cool cover is placed over a hot furnace and when a hot cover on a furnace is removed into a region of comparatively cool air. Normal ingot furnace temperatures range between 22002500 F. and there is a considerable temperature drop between the lower surfaces of the blocks which are exposed to the furnace temperatures and the upper surfaces of the blocks which are exposed to the relatively cool outside atmosphere. Repairing and rebuilding the refractory structure of the cover is an expensive operation and may cause even more expensive production delays. Great care in handling of the cover will prolong the life of the blocks but this is only a partial solution and is so time consuming as to odset the advantages of postponing repairs.

Reinforcing refractory blocks so that they will remain in service for an extended period of time presents difficult problems which have heretofore not been solved satisfactorily. tringers have been run beneath the blocks to support their lower surfaces but such stringers must be made of special and expensive materials to with stand the heat of the furnace and to prevent a reaction with the silica in the blocks. The reaction product with an iron or steel support would be a silicon dioxide slag which would liquify at furnace temperature and hence would melt away the blocks over the support. Extending stringers between the blocks instead of beheath them would present not only possible silica reaction problems but also diflicult problems of arranging the blocks around the supports and of excessive heat loss through the heat conductive metal of the stringers.

My invention makes it possible to reinforce refractory blocks and to extend their effective life without suffering the disadvantages mention-ed above. My invention will best be understood with reference to the following detailed description and to the accompanying drawings. I have shown in the drawings, for purposes of illustration only, a preferred embodiment of my invention, in which:

Figure 1 is a perspective view of a soaking pit cover incorporating my invention and broken away to show the details of construction; and

Figure 2 is a front view of a suspended refractory block behind a reinforcing sheet.

Referring in detail to the drawings, the portion of a soaking pit cover shown in Figure 1 is sup ported by a steel beam H3 extending over a series of parallel steel beams or stringers Ii, I2, l3 and I4. Fastening plates l5 and I6 engage a flange l l of the beam i0 and are bolted to the stringers H and I2 and to the stringers i3 and it respectively to fasten the stringers to the supporting beam [0. In order to provide means for suspending refractory blocks from the stringers the stringer H has a flange is extending toward the stringer [2, the stringer [2 has a flange it extending toward the stringer II, the stringer i3 has a flange 26 extending toward the stringer It and the stringer M has a flange 2| extending toward the stringer I3.

Successive parallel courses of refractory blocks extend transversely beneath the stringers H, l3 and I4, and each course consists of alternate suspended blocks and intermediate blocks keyed between the suspended blocks. For example, in the foremost course of blocks illustrated in Figure 1, a block 22 is suspended from the stringers H and 12, a block 23 is suspended between the stringers I3 and i4 and an intermediate block 24 is positioned between and supported by the blocks 22 and 23. A similar intermediate block. 25 on the other side of the suspended block 23 is supported by and between the suspended block 23 and the next suspended block (not shown).

The suspended blocks each have an upper hanger portion adapted to be engaged and supported by the pair of stringers above the block and an integral lower body portion suspended from the hanger portion. As shown in Figure 2, the suspended block 22 has a body portion 22a, an intermediate neck portion 22b and an enlarged upper portion 220. The neck 22b and the enlarged portion 220 form a generally, ii-shaped hanger parallel faces at the front and rear of the block. The enlarged portion 220 has an overhanging lower surface 25 resting on the flange i8 and has an overhanging lower surface 2;? r sting on the flange H9. The suspended block 23 is similarly formed and has an overhanging lower surface 28 resting on the flange 2i! and an overhanging lower surface (not. shown) resting on the flange 21. The intermediate blocks 24 and 25 each have upper extensions 3i].on either side by which the said intermediate blocks are supported in grooves 3| in the sides of the suspended blocks 22 and 23. Successive parallel courses of refractory blocks extend behind the foremost course shown in Figure 1 so that an even row of blocks beginning with a block 32 is suspended from the stringers II and I2 behind the block 22. A similar row of blocks beginning with a block 33 is suspended from the stringers i3 and Hi behind the block 23. An even row of intermediate blocks beginning with a block 3 3 extends behind the intermediate block 24 and is supported between the two rows of blocks suspended from the stringers H, [2, l3-and hi; A similar even row of intermediate blocks extends behind the block 25. Continuations of these evenv rows of blocks extend in front of the foremost course shown in Figure 1 but are broken away and not shown in Figure 1.

Layers of insulating material 35 are spread over the successive courses of blocks between the necks of the suspended blocks and similar insulating material 36 is spreadbetween each pair of stringers over the enlarged portions of the. suspended blocks carried by the stringers. The construction so far described is conventional in soaking pit covers and the like.

In accordance with my invention, sheets of reinforcing material are secured between adjacent courses of the refractory blocks with an edge of each sheet engaging a supporting stringer.

The reinforcing sheets are preferably of 20-to 22- gauge steel but steel sheets as thick as of an inch may be used. Steel sheets of; 20-22 gauge are preferred because they are thin enough to minimize heat losses caused by conduction of heat through the sheets and yet are strong enough to reinforce the courses of-the refractory blocks effectively. Referring to the preferred embodiment of my invention shown in the drawing, 22 gauge steel sheets areinserted between each pair of adjacent suspended blocksto the left of the row of suspended blocks behindthe block 22 are removed to show theextensions 3i of-the sheets between the saidrow ofsuspended blocks, and a sheet 38 is shown against the exposed face of the block 22 and a sheet 33 is shown against the exposed faceof the block extending between two vertical; and

23. Figure 2 shows more clearly the outline of the sheet 38 against the suspended block 22. Each sheet is perforated as shown at 40 in the sheet 33 and as shown at 4| in the sheet 253 so that the sheets may be securely mortared between the adjacent suspended and intermediate blocks. The mortar fiii-fiows through the perforations and after the mortar hardens it opposes any movement of the sheets between the adjacent blocks. The peripheral edges of each sheet are spacedinwardly of the peripheral edges of the adjacent suspended block faces except where the sheet extends between the intermediate blocks on either side of the suspended blocks and except where the sheet bears against the stringer flanges from which the adjacent suspended blocks are suspended. For example, the sheet 38 is shown in Figure 2 engaging the flange 18 at 42 and engaging the flange IE3 at 33.

The steel sheets are securely bondedbetween the adjacent blocks and engage the stringers thereabove so that failure of the hanger portions of either of the adjacent suspended blocks will not cause the block having the cracked hanger to fall down into the furnace or to add its weight to the load which must be supported by the hangers of adjacent suspended blocks. Moreover, the sheets extend adjacent the lower edges of the suspended and intermediate blocks and hold up pieces of the adjacent blocks which might otherwise break away as a result of spalling action. The peripheral edges-of the sheets are withdrawn from the exposed surfaces of the blocks in order to prevent the sheets as far as possible from receiving and transmitting an excessive amount of furnace heat and also to bury the sheets in the courses of blocks so that they are protected from the oxidizing atmosphere of the furnace and are thus prevented from reacting with the blocks to form a liquid slag. The fact that the sheets do conduct some heat is not a disadvantage because it tends to equalize the temperatures at the upper and lower portions of the blocks and thereby reduces spalling of the blocks as a result of uneven thermal contraction and expansion. The sheets are in edgewise contact with the supporting stringer. flanges and thus minimize heat conduction from the sheets to the stringers.

The reinforced refractory structure of my invention has anextended service life because the reinforcing sheets hold the blocks in place after they have become cracked and it has the further advantage of permitting substitution of less expensive kinds of refractory blocks for the high quality blocks which would be necessary in the absenceof my reinforcing sheets. The reinforcing sheets do not cause excessive heat losses and have substantially no chemical reaction with the blocks.

Although I have illustrated. and described a preferred embodiment of my invention, it will be recognized that changes in the details and arrangements may be made without departing from the spirit of the invention or the scope of the appended claims.

I claim:

1. A top structure for a heating chamber comprising a cover of refractory blocks extending generally horizontally over the chamber, a supporting structure extending generally over the blocks, at least some of the blocks each having an upward extension in supported engagement with the supporting structure and'having a vertical face along the block and its upward extensionclosely opposedto a like face of a like block,

and single pieces of substantially unoxidized sheet metal sandwiched and bonded on both sides in air-tight relation between such opposed faces of adjacent blocks substantially from top to bottom of the blocks and their upward extensions, whereby the metal pieces prevent lower portions of blocks to which the pieces are bonded from dropping into the heating chamber after such lower portions become cracked away from their supporting upward extensions during operation of the chamber.

2. A top structure for a heat-treating chamber for ingots of iron and the like comprising a cover of refractory blocks extending generally horizontally over the chamber, a supporting structure extending generally over the blocks, at least some of the blocks each having an upward extension in supported engagement with the supporting structure and having a vertical flat face of the block and its upward extension closely opposed to a like face of a like block, and single perforated and entirely smooth-surfaced pieces of thin sheet steel sandwiched between and solidly mortar-ed on both sides to such opposed faces of adjacent blocks substantially from top to bottom of the blocks and their upward extensions, whereby the steel pieces are bonded to adjacent blocks and their upward extensions to prevent lower portions of the blocks from dropping into the heating chamber after such lower portions become cracked away from their supporting upward extensions during operation of the chamber.

3. A top structure for a heating chamber comprising a supporting structure extending over the chamber, courses of refractory blocks suspended from and generally beneath the supporting structure, single pieces of sheet steel sandwiched between adjacent blocks, and refractory mortar solidly embedding and covering both sides of each of said pieces adjacent the bottoms of the blocks, each of said sides of the pieces being bonded to the adjacent block and being protected against exposure to oxidizing gases from the heating chamber.

4. A top structure for a heating chamber comprising a supporting structure extending over the chamber, courses of refractory blocks suspended from and generally beneath the supporting struc-- ture, single pieces of sheet steel sandwiched between adjacent blocks, and refractory mortar solidly embedding and covering both sides of each of said pieces adjacent the bottoms of the blocks, whereby the pieces are protected against exposure to oxidizing gases from the heating chamber, said pieces being heat-bonded to the refractory mortar and adjacent blocks by heat from the heating chamber.

5. A top structure for a heating chamber comprising a pair of spaced longitudinal supporting members extending generally horizontally over the chamber, a first course of refractory blocks suspended from and generally beneath one of said members, a second course of refractory blocks spaced from the first course and suspended from and generally beneath the other supporting member, said blocks in the first and second courses having upward extensions in supported engagement with the respective supporting members thereabove, a third course of refractory blocks closing the space between the first and second courses, and pieces of sheet steel, some of said pieces each being sandwiched and bonded between adjacent blocks and their upward extensions in the first course and also between adjacent blocks in the third course, and some of said pieces each being sandwiched and bonded between adjacent blocks and their upward extensions in the second course and also between adjacent blocks in the third course, whereby said pieces of sheet steel serve to hold the three courses together and to the supporting members after cracking of the blocks during operation of the heating chamber.

6. A top structure for a heating chamber comprising a pair of spaced longitudinal supporting members extending generally horizontally over the chamber, a first course of refractory blocks suspended from and generally beneath one of said members, a second course of refractory blocks spaced from the first course and suspended from and generally beneath the other supporting member, a third course of refractory blocks closing the space between the first and second courses, and pieces of sheet metal, some sandwiched, contacting and fastened between adjacent blocks in the first course and extending between and into contacting relation with adjacent blocks in the third course, and some sandwiched, contacting and fastened between adjacent blocks in the second course and extending between and into contacting relation with adjacent blocks in the third course, whereby said pieces of sheet metal serve as supporting connections between the third course and the supported first and second courses.

7. In a suspended arch structure including metal supporting members, rows of refractory tile, each row comprising hanger tile suspended from the metal supports and facing tile suspended from said hanger tile disposed between adjacent hanger tile, and sheet metal spacers between adjacent rows of said tile being independently supported from said metal framework and of a shape to overlap the joints of said hanger and facing tile.

8. A top structure for a heating chamber comprising a pair of spaced longitudinal supporting members extending generally horizontally over the chamber, a first course of refractory blocks suspended from and generally beneath one of said members, a second course of refractory blocks spaced from the first course and suspended from and generally beneath the other supporting member, a third course of refractory blocks closing the space between the first and second courses, and pieces of sheet metal, some of said pieces each being sandwiched and fastened between opposed faces of adjacent blocks in the first course and also between opposed faces of adjacent blocks in the third course, and some of said pieces each being sandwiched and fastened between opposed faces of adjacent blocks in the second course and also between opposed faces of adjacent blocks in the third course, the sides of both sets of pieces each being in essentially direct contact with each of the adjacent opposite block faces, whereby said pieces of sheet metal serve as supporting connections between the third course and the supported first and second courses.

JOHN RAWLINGS.

References Cited in the file Of this patent UNITED STATES PATENTS Number Name Date 1,500,240 Griffith July 8, 1924 1,913,168 Longenecker June 6, 1933 2,187,669 Stewart Jan. 16, 1940 2,229,869 Koch Jan. 28, 1941 2,476,423 Longenecker July 19, 1949 

